The present invention relates to a novel phthalocyanine compound, a process for producing the compound, and use of the compound.
More particularly, the present invention relates to a novel phthalocyanine compound absorbing in the near-infrared region of 700xcx9c1000 nm of the spectrum and useful for information recording systems utilizing laser light (such as optical cards, organic photoconductors, laser thermal transfer recording, laser thermal recording, laser direct printing plate making, etc.) and devices required to have near-infrared light absorbing properties (such as near-infrared light-absorbing filter, thermal-ray screening film, protective goggles, secret ink, agricultural film, etc.) and to a process for producing the compound.
Certain phthalocyanine compounds have good near-infrared absorbing properties and, therefore, there is a mounting interest in the application thereof to optical cards, near-infrared light-absorbing filters, thermal-ray screening film, protective goggles, laser direct printing plate making, laser thermal transfer recording, laser thermal recording, organic photoconductors for laser printer, etc.
The following compounds A and B are described in Example 13 and Example 20, respectively, in Tokkyo Kokai Koho (Japanese laid-open patent gazette) H8-60008. 
However, these compounds A and B absorb not only in the near-infrared region but also in the visible region of the spectrum so that the scope of their application is limited. For example, in the field of the near-infrared light-absorbing filter for plasma display, secrete ink, etc., there exists a demand for a phthalocyanine compound which absorbs much in the near-infrared region and very little in the visible region of the spectrum (500-600 nm in particular).
The present invention has for its object to provide a phthalocyanine compound which absorbs in the wavelength region of 700xcx9c1000 nm and satisfies the requirements of said various applications. The present invention has for another object to provide a process for producing said phthalocyanine compound in high yield.
The inventors of the present invention did much research for overcoming the above-mentioned disadvantages and found that these disadvantages can be overcome by a phthalocyanine compound having an acyl or aroyl group introduced onto the nitrogen atom on each benzothiazine ring of the phthalocyanine nucleus.
The present invention, in the first aspect thereof, is directed to a phthalocyanine compound of the following general formula (I). 
wherein R1, R2, R3, R4, R5, R6, R7 and R8 each represents alkyl or alkoxyalkyl; X1, X2, X3, X4, X5, X6, X7 and X8 each represents sulfur or  greater than NR9; X1=(either X3 or X4)=(either X5 or X6)=(either X7 or X8)=sulfur and X2=(the other one of X3 and X4)=(the other one of X5 and X6)=(the other one of X7 and X8)= greater than NR9; R9 represents an acyl group which may optionally be substituted or an aroyl group which may optionally be substituted; M represents a couple of hydrogen atoms, a divalent metal, a trivalent metal derivative or a tetravalent metal derivative).
The present invention relates, in a second aspect thereof, to a method of producing a phthalocyanine compound of the above general formula (I) which comprises reacting a phthalocyanine compound of general formula (II) with an acid anhydride of general formula (III) or an acid halide of general formula (IV). 
wherein R1xcx9cR8 are as defined above; Y1, Y2, Y3, Y4, Y5, Y6, Y7 and Y8 each represents sulfur or  greater than NH and Y1=(either Y3 or Y4)=(either Y5 or Y6)=(either Y7 or Y8)=sulfur and Y2=(the other one of Y3 and Y4)=(the other one of Y5 and Y6)=(the other one of Y7 and Y8)= greater than NH; M represents a couple of hydrogen atoms, a divalent metal, a trivalent metal derivative or a tetravalent metal derivative.
(R9)2Oxe2x80x83xe2x80x83(III)
wherein R9 represents an acyl group which may optionally be substituted or an aroyl group which may optionally be substituted.
R9X9xe2x80x83xe2x80x83(IV)
wherein R9 is as defined above; X9 represents halogen.
The present invention relates, in a third aspect thereof, to a near-infrared absorbing material comprising the phthalocyanine compound according to said first aspect of the present invention.
The present invention relates, in a fourth aspect thereof, to an original plate for direct printing plate making which comprises a photothermal conversion layer containing the phthalocyanine compound according to said first aspect of the invention as disposed on a support.